The production of passenger vehicles around the world reached an all-time high this year: 80 million new cars and light trucks, according to a study by the Worldwatch Institute in Washington. The new production record is heightening concerns among environmentalists, since petroleum-fueled automobiles are a major source of air pollution and climate-changing carbon emissions.

With the new cars and light trucks added to the global fleet, the world is nearing a milestone - one billion vehicles on the roads. Most are petroleum-fueled internal combustion engines, whose emissions cause environmental problems like air pollution and contribute to global warming.

Michael Renner of the Worldwatch Institute, wrote the analysis of worldwide auto production.

The strongest producer by far right now is China, which had a tremendous period of growth over the last decade and have overtaken Germany, Japan and the U.S., which used to be the three big producers worldwide," Renner said.

Hybrid and electric vehicles represent less than two percent of the total output, the study says.

But representatives of the auto industry say they care about the environment. Steven Brooks, an analyst at Edmunds.com, which compiles data on the automobile market, says the industry is responding to the desire for greener products.

“There are 43 different vehicles that are going to get introduced into the shopping arena by the end of 2015, like this Honda CR-Z here. This is a hybrid electric vehicle,” Brooks said.

But Renner says unless we move to cleaner and more efficient fuels, as well as alternative propulsion systems, electric cars won't solve the environmental problem.

“If we don’t significantly change the bases on which our electricity systems are functioning, in other words if we use large amounts of coal and fossil fuels to produce electricity, then going with the electrical vehicles is not getting us all that far,” Renner said.

Industry experts say hydrogen fuel cells and experimental new materials, such as strong, lightweight magnesium and carbon composites, could dramatically improve energy efficiency in tomorrow's passenger vehicles. But such improvements are still years away. In today's car market, Steven Brooks says, gasoline prices are still driving people’s vehicle choices.

“The mid-size sedans are still the number-one-selling segment in the country, but the adoption of the small and hybrid vehicles is on the rise as the gas prices go up,” Brooks said.

According to the United Nations, emissions from road transport constitute more than 20 percent of greenhouse gases.

The Worldwatch study notes that even in developing countries, car travel distances have doubled in the past decade. Experts agree that to counter the public health and environmental impact of this trend, governments must develop better systems of public transportation.